The recent successive findings of the many advantageous features of maltose have led to the rapid expansion of uses for maltose. Thus, saccharified starch products, wherein maltose is the predominant constituent, are drawing much attention and receiving ever-increasing demand from many fields, especially from the food processing and pharmaceutical industries.
Conventionally, saccharified starch hydrolysates with a maltose purity in the range of 40-50% were obtained by subjecting liquefied starch to the action of a maltogenic enzyme, malt amylase. More recently, with the employment of starch-debranching enzyme and beta-amylase, saccharified starch hydrolysates with a maltose purity of 50% or higher have become obtainable with considerable ease.
Maltotriose, necessarily, forms abundantly in saccharified starch hydrolysates which are prepared from starch with maltogenic enzyme(s), for example beta-amylase and starch-debranching enzyme, and wherein maltose is the predominant constituent. Since the formed maltotriose is not decomposable by such enzymes, the increment of maltose purity was so far restricted. Thus the inventors found that decomposition or conversion of the maltotriose present in said hydrolysates into maltose is required to improve further the maltose purity.